Ni-rich Schottky contact
View Patent ↗Embodiments of a Nickel-rich (Ni-rich) Schottky contact for a semiconductor device and a method of fabrication thereof are disclosed. Preferably, the semiconductor device is a radio frequency or power device such as, for example, a High Electron Mobility Transistor (HEMT), a Schottky diode, a Metal Semiconductor Field Effect Transistor (MESFET), or the like. In one embodiment, the semiconductor device includes a semiconductor body and a Ni-rich Schottky contact on a surface of the semiconductor body. The Ni-rich Schottky contact includes a multilayer Ni-rich contact metal stack. The semiconductor body is preferably formed in a Group III nitride material system (e.g., includes one or more Gallium Nitride (GaN) and/or Aluminum Gallium Nitride (AlGaN) layers). Because the Schottky contact is Ni-rich, leakage through the Schottky contact is substantially reduced.
1. A semiconductor device comprising:
a semiconductor body; and
a Nickel-rich Schottky contact on a surface of the semiconductor body, the Nickel-rich Schottky contact comprising a Nickel-rich contact metal stack;
wherein the Nickel-rich contact metal stack comprises:
a first Nickel layer directly on the surface of the semiconductor body;
an interlayer directly on a surface of the first Nickel layer opposite the semiconductor body; and
a second Nickel layer directly on a surface of the interlayer opposite the first Nickel layer;
wherein a ratio of a total thickness of the first Nickel layer and the second Nickel layer to a thickness of the interlayer is greater than 3.
2. The semiconductor device of claim 1 wherein the interlayer is a Platinum layer.
3. The semiconductor device of claim 1 wherein the interlayer is a Palladium layer.
4. The semiconductor device of claim 1 wherein the interlayer is an Iridium layer.
5. The semiconductor device of claim 1 , wherein a material for the interlayer is selected from one of Platinum, Palladium, or Iridium.
6. The semiconductor device of claim 5 wherein a thickness of the interlayer is in a range of and including 50 to 200 Angstroms.
7. The semiconductor device of claim 5 wherein the ratio of the total thickness of the first Nickel layer and the second Nickel layer to the thickness of the interlayer is approximately equal to 3.33.
8. The semiconductor device of claim 5 wherein the ratio of the total thickness of the first Nickel layer and the second Nickel layer to the thickness of the interlayer is in a range of and including 3 to 10.
9. The semiconductor device of claim 5 wherein the ratio of the total thickness of the first nickel layer and the second nickel layer to the thickness of the interlayer is in a range of and including 3 to 4.
10. The semiconductor device of claim 5 wherein a thickness of the first Nickel layer is in a range of and including 100 to 300 Angstroms, the thickness of the interlayer is in a range of and including 50 to 180 Angstroms, and a thickness of the second Nickel layer is in a range of and including 50 to 250 Angstroms.
11. The semiconductor device of claim 5 wherein the Nickel-rich Schottky contact further comprises a contact layer directly on a surface of the second Nickel layer opposite the interlayer.
12. The semiconductor device of claim 11 wherein the contact layer is a Gold layer.
13. The semiconductor device of claim 11 wherein the Nickel-rich Schottky contact further comprises a protection layer directly on a surface of the contact layer opposite the second Nickel layer.
14. The semiconductor device of claim 13 wherein the protection layer is a Titanium layer.
15. The semiconductor device of claim 13 wherein the contact layer is a Gold layer, and the protection layer is a Titanium layer.
16. The semiconductor device of claim 5 wherein the Nickel-rich Schottky contact further comprises:
a first contact layer directly on a surface of the second Nickel layer opposite the interlayer;
a barrier layer on a surface of the first contact layer opposite the second Nickel layer; and
a second contact layer on a surface of the barrier layer opposite the first contact layer.
17. The semiconductor device of claim 16 wherein the barrier layer is a Platinum layer.
18. The semiconductor device of claim 17 wherein the first and second contact layers are Gold layers.
19. The semiconductor device of claim 16 wherein the barrier layer is a Nickel layer.
20. The semiconductor device of claim 19 wherein the first and second contact layers are Gold layers.
21. The semiconductor device of claim 5 wherein the semiconductor body comprises one or more Group III nitride epitaxial layers.
22. The semiconductor device of claim 21 wherein the one or more Group III nitride epitaxial layers comprise at least one of a group consisting of: a Gallium Nitride layer and an Aluminum Gallium Nitride layer.
23. The semiconductor device of claim 21 further comprising a Silicon Carbide substrate, wherein the semiconductor body is on a surface of the Silicon Carbide substrate.
24. The semiconductor device of claim 5 wherein the semiconductor device is a radio frequency power device.
25. The semiconductor device of claim 5 wherein the semiconductor device is a radio frequency device.
26. The semiconductor device of claim 5 wherein the semiconductor device is a power device.
27. A semiconductor device comprising:
a semiconductor body; and
a Schottky contact on a surface of the semiconductor body, the Schottky contact comprising:
a first Nickel layer directly on the surface of the semiconductor body;
an interlayer directly on a surface of the first Nickel layer opposite the semiconductor body; and
a second Nickel layer directly on a surface of the interlayer opposite the first Nickel layer;
wherein the interlayer comprises a transition metal other than Nickel.
28. The semiconductor device of claim 27 wherein a ratio of a total thickness of the first Nickel layer and the second Nickel layer to a thickness of the interlayer is greater than 1.